Gaseous nitrogen is used in many industrial applications. For example, gaseous nitrogen may be used to purge tanks of air which are to be filled with chemicals that are reactive with air. Also, gaseous nitrogen is used in various oil-field operations such as in fracturing a formation or in completing a well by freeing the drill pipe of drilling mud.
Nitrogen is shipped and stored as a very cold liquid having a boiling point of -195.8.degree. C. Before nitrogen can be used in the form of a gas, it is, therefore, necessary that the liquid nitrogen be gassified. This is commonly done by using a burner that generates hot combustion gases which contact heat exchanger tubes to impart heat to nitrogen within the tubes to convert the liquid nitrogen to a gas. In gassifying liquid nitrogen for a particular use, only enough nitrogen is gassified as is required for the particular use. Also, in a use application for gaseous nitrogen, the particular application may be interrupted so that the need for gaseous nitrogen is momentarily halted, then resumed at a later time, etc. In any application where the need for gaseous nitrogen is temporarily halted, the burner which is used in gasifying liquid nitrogen will generally be shut down and will then be restarted when there is a further need for gaseous nitrogen. This has created problems because delays may occur because of difficulties in restarting the burner, particularly, for example, in an arctic environment where oil field operations may be carried out.
When there are delays in restarting a burner used for the gasification of nitrogen, this may be quite costly since it may delay the drilling of an oil well or the loading of a large ship, etc. At the same time, it is costly to operate a burner merely to keep the burner in readiness even though the burner is not needed at that particular time for the gasification of nitrogen.
Accordingly, it would be desirable if a burner could be provided which could be easily shut down and restarted without any lengthy delays. Such a burner could be used intermittently and could still be shut down when not in use so as to conserve on the use of fuel.